Re: [PATCH] xen-pvdevice: Introduce a simplistic xen-pvdevice save state

[Stefano Stabellini <sstabellini@kernel.org>]

On Thu, 8 Mar 2018, Igor Druzhinin wrote:
> This should help to avoid problems with accessing the device after
> migration/resume without PV drivers. Older systems will acquire
> the new record when migrated which should not change their state for
> worse.

Could you please explain what problems this patch is helping avoid? And
also how this patch is helping exactly?

Please add more concrete info.


> Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
> ---
>  hw/i386/xen/xen_pvdevice.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/hw/i386/xen/xen_pvdevice.c b/hw/i386/xen/xen_pvdevice.c
> index c093b34..ef22a03 100644
> --- a/hw/i386/xen/xen_pvdevice.c
> +++ b/hw/i386/xen/xen_pvdevice.c
> @@ -71,6 +71,16 @@ static const MemoryRegionOps xen_pv_mmio_ops = {
>      .endianness = DEVICE_LITTLE_ENDIAN,
>  };
>  
> +static const VMStateDescription vmstate_xen_pvdevice = {
> +    .name = "xen-pvdevice",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_PCI_DEVICE(parent_obj, XenPVDevice),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  static void xen_pv_realize(PCIDevice *pci_dev, Error **errp)
>  {
>      XenPVDevice *d = XEN_PV_DEVICE(pci_dev);
> @@ -120,6 +130,7 @@ static void xen_pv_class_init(ObjectClass *klass, void *data)
>      k->class_id = PCI_CLASS_SYSTEM_OTHER;
>      dc->desc = "Xen PV Device";
>      dc->props = xen_pv_props;
> +    dc->vmsd = &vmstate_xen_pvdevice;
>  }
>  
>  static const TypeInfo xen_pv_type_info = {
> -- 
> 2.7.4
> 

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